Clifford was a twenty-four-year-old horse trainer when he enlisted at Liverpool NSW in December 1915. He, and his parents John and Annie Stevens, lived at Ashford.
Clifford became a member of the 7th Light Horse Regiment, 16th Reinforcement and sailed from Australia for Egypt on HMAT A56 Palermo in April 1916. He became ill and spent time in hospital at Abbassia before being sent to England for treatment. He returned to Egypt in March 1917 and attended a Lewis Gun instruction course. At the end of the year, he was ill again and needed hospital treatment for a month. Clifford returned to Australia by hospital ship in June 1919 and was medically discharged in January 1920. His name is recorded on the Ashford Honor Roll.